Mazánek Vlastimil, Luxa Jan, Matějková Stanislava, Kučera Jan, Sedmidubský David, Pumera Martin, Sofer Zdeněk
Department of Inorganic Chemistry , University of Chemistry and Technology Prague , Technická 5 , 166 28 Prague 6, Czech Republic.
Central Analytical Laboratory , Institute of Organic Chemistry and Biochemistry of the Academy of Sciences of the Czech Republic , 166 10 Prague 6, Czech Republic.
ACS Nano. 2019 Feb 26;13(2):1574-1582. doi: 10.1021/acsnano.8b07534. Epub 2019 Jan 17.
Graphene and its derivatives have been reported in many articles as "metal-free" carbon electrocatalytic materials. Its synthesis procedures are generally based on the chemical oxidation of graphite and subsequent thermal or chemical reduction. Because graphene oxide has a large surface area and typically contains a variety of oxygen functionalities, metallic ions (impurities) from reaction mixtures can be adsorbed on its surface. These impurities can significantly enhance the electrocatalytic activity and thus lead to data misinterpretation; such impure samples are referred to as "metal-free" catalysts. In this paper, we report the synthesis of impurity-free graphene, which is compared with graphene prepared by standard methods based on the thermal and chemical reduction of two graphene oxides. Detailed analysis of graphene prepared by standard methods shows a direct relation between metallic impurities and the electrocatalytic activity of graphene. In contrast, impurity-free graphene exhibits poor electrocatalytic activity.
石墨烯及其衍生物在许多文章中被报道为“无金属”碳电催化材料。其合成过程通常基于石墨的化学氧化以及随后的热还原或化学还原。由于氧化石墨烯具有较大的表面积且通常含有多种氧官能团，反应混合物中的金属离子（杂质）会吸附在其表面。这些杂质会显著提高电催化活性，从而导致数据误判；这种不纯的样品被称为“无金属”催化剂。在本文中，我们报道了无杂质石墨烯的合成，并将其与通过两种氧化石墨烯的热还原和化学还原的标准方法制备的石墨烯进行了比较。对通过标准方法制备的石墨烯的详细分析表明，金属杂质与石墨烯的电催化活性之间存在直接关系。相比之下，无杂质石墨烯表现出较差的电催化活性。
